The "best scenario" isn't really the best scenario. You will confuse a whole bunch of non-technical users by including more than one web browser. Then Microsoft or Apple end up having to support whatever browsers they ship so it becomes their problem as well. And it doesn't and won't happen in real life - not just Windows but Mac OS X, Ubuntu, iPhone, WebOS or Android. And there's also advantages to including a consistent rendering engine with an OS as anyone who has used Steam can tell you.
It's also interesting you say that Microsoft managed to rename the web "Internet Explorer" because in Tim Berners-Lee's book he says that after Mosaic was launched and was beginning to become popular the people behind Netscape were trying to rename the web themselves and he wasn't very happy about that.
It's also interesting you say that Microsoft managed to rename the web "Internet Explorer" because in Tim Berners-Lee's book he says that after Mosaic was launched and was beginning to become popular the people behind Netscape were trying to rename the web themselves and he wasn't very happy about that.